Qwiic single relays returning 255/0xFF from getState after a few state changes

Qwiic System
1

My system has 3 Qwiic single relays in it. Two of them (LA1 and LA2) control a linear actuator and the other is used to reset another device (RES).

After three or four on/off actions the LA1 and LA2 relays start returning a status of 0xFF (instead of 0x00 or 0x01).

I can reproduce this 100%, although the number of on/off’s varies. I can reproduce this by only turning on/off one of the relays, or both.

However, on the RES relay (which has no load attached) I cannot reproduce this.

I suspect I’m getting flyback (?) noise from the linear actuator when it turns off.

I’m running the LA at 12V and the specs say the full load current at 12V is 5.0A. The Qwicc relays say they are rated at 5A at 12V, so there shouldn’t be a problem.

https://cdn.shopify.com/s/files/1/0061/ … 5827680058

Do I need flyback diodes?

2

There is already a flyback diode on the coil of the relay.

It could be inductive from the coil and thus a diode on the coil. One could add an extra capacitor there as well.

It could be an inductive spark when switching the linear actuator, as you switch DC a diode on the contacts can help.

It could also be sparks between the contacts for a very short moment during switching. As you switch DC a capacitor on the contacts can help in that case.

One can also add a capacitor on the switching power to eliminate high-frequency spikes.